Improvement in anastatic printing



UNITED STATES PATENT OFFICE.

G. F. BALDAMUS AND F. W. SIEMENS, OF BERLIN, PRUSSIA.

IMPROVEMENT IN ANASTATIC PRINTING.

Specification forming part of Letters Patent No. 4,239, dated October25, 1845.

To all whom it may concern:

Be it known that we, CARL FRIEDRICH BAL- DAMUS, of Berlin, in theKingdom of Prussia, and F. W. SIEMENS, of the same place, have inventedImprovements in Producing and Multiplying Copies of Designs andImpressions of Printed or Written Surfaces; and we do hereby declarethat the following is a full and exact description thereof.

Our invention of improvements in producing and multiplying copies ofdesigns and impressions of printed or written surfaces consists in theprocess whereby we obtain transfers or reversed fac-similes on metallicsurfaces from designs or writings in lithographic ink and from printsand printin gin general; and as this process is applicable to thereprinting of oldworks we propose to term it anastatic printing. Theimprovement for obtaining transfers or-reversed fac-similes consists ofseveral distinct operations, and will be best under stood by a simpledescription of each.

First. The surface to receive a reversed copy of the design or print maybe of brass, steel, iron, copper, zinc, or other convenient metal;

but we prefer zinc to any other metal in consequence of the greaterfacility of management which it admits. It may be used as plates orcylinders, and in each case requires to be perfectly homogeneous and topresent a clean surface. We prefer polished surfaces, and prepare theplate by grinding it with emery and water, applied by means of a clothrubber, so as to produce fine parallel lines from end to end or fromside to side, but not crossing each other more than can be avoided. Whenthe surface has acquired a uniform appearance We rub the dirt and wateroff with clean blotting-paper and polish the plate with another clothand dry fine emery, or with fine emerypaper, in the same paralleldirection as before, taking care not to touch the surface with the handor any dirty or oily substance. We next rub off all dust and dirt withclean blottingpaper until it is perfectly clean and free from oxide andpresents a surface polished in a parallel direction for receiving theink.

Second. The design or writing to be copied and printed must be executedin ink of a saponaoeous or fatty nature-such as common litho-- graphicor printing ink-and may be on any clean well-sized paper. These may betransferred either when quite new or when many years old, or aftertraveling from one country to another. The designs or printed papers,which throughout this specification we call originals, are then chargedwith any convenient acid, which we prefer to be nitric. Any originals sofresh as to yield an impression to a piece of clean paper when pressedfirmly together by means of a burnisher we treat thus: We laythe writtenor printed side on a clean piece of blotting-paper and wet the upperside equally by means of a soft brush with a mixture of one part ofnitric acid of 1.362 specific gravity and eight parts of water, byweight. So soon as the acid has completely soaked through the originalswe lay it between sheets of blotting-paper and remove the excess ofdilute acid by gentle pressure, and if the acid has equally penetratedthe originals we lay its written surface on the cleaned metallicsurface, place double blottingpaper over it, and pass it underconsiderable rolling pressure, which'causes the acid to attack the metalwhere unprotected by the writing, drawing, or printing, &c., on theoriginals and produce what we call a negative etching. The original maybe thus pressed between two metallic surfaces without any blotting-paperwhen it is desired to obtain a reversed counterpart from each side. Theoriginals may be immediately removed, and a reversed impression shouldbe perceived in all parts of the plate distinct from the etched surface.Prints of more than'two months old have their ink more indurated andrequire a modification of the above treatment of transferring, which maybe effected as follows: We first lay a sheet of blank white paper in thebottom of a fiat porcelain or glass vessel large enough to contain theoriginal, and then lay as many originals alternately with blank ones aswe require to transfer; but if the original is thick and strong theintermediate papers may be omitted. We next pour over the whole mass asufficient quantity of nitric acid of about 1.362 specific gravity tosoak through the mass of paper, and then cover the basin or vessel witha plate of glass and let it remain for from twelve hours to seven days,according to the age and nature of the print, for which sider that theoriginals have been sufficiently acted on by the acid we remove thecover and add water so as to reduce the strength of the acid containedin each sheet to such a degree as that it shall not act strongly ordisagreeably on the tongue when brought into contact.

. We now lay the originals between sheets of clean blotting-paper andsubject them to slight pressure to remove superfluous moisture. We thenlay it on the polished metallic surface, as before described, andsubject it to much greater rolling pressure than recent originals. Ifsaving of time is an object and when the originals have been very muchindurated and dried, as in engravings, &c., we proceed by washing overthe back of the original to be transferred with a solution of causticpotash in pure rain or distilled water of about 1.0 14 specific gravity,which we prefer to carbonate of potash, as that substance would evolvegas in the next process; and when the original is fully soaked weprepare a saturated solution of tartaric acid in water in a shallow flatbasin or on a sheet of glass with a wax border to form tank sides. Wethen place the original, which has been soaked in caustic potash, inthis solution with the face to be transferred uppermost, and a reactiontakes place between the tartaric acid and potash in the paper, formingcrystals of cream of tartar, which appear over the whole surface and aresparingly soluable in Water, leaving only those parts which areprotected with printing-ink uncovered with crystals. We next roll a hardlithographic inking-roller charged with a small portion of ink over itswet surface several times and in several directions until the blacklines become revived by a' new coat of ink, leaving the blank part ofthe paper covered with crys als almost untouched. We next'remove thesuperfluous ink by a second application of a hard roller uncharged withink, and dissolve the crystals of cream of tartar by immersing the paperfor some hours in dilute nitric acid, twenty parts wai er by one partacid of 1.362 specific gravity, by weight, after which it is partiallydried in blotting-paper, placed on the metallic surface, and subjectedto slight pressure, as before.

Instead of using printing-ink, as before described, for reviving theprint so as to protect the metallic surface from the action of the acid,we sometimes employ the vapor ofconvenient volatile oils to effect thesame object, as that of oil of turpentine.

Having now described our process of transferring reversed fac-similes ofnew and old designs and printed surfaces to the met allic plate,

we proceed to explain the next operation for completing theirpreparation as printing-surfaces.

We remove the originals from the plate after pressure and wash the plateover in all directions with a very thick gum-water by means of a sponge,and next rub up or fill in the plate with linen rag or sponge chargedwith a mixture of lithographic printing-ink and gum-water, whenever ithas been protected from the action-of the acid, which operation ofcharging the plate constantly follows the continuous washing with gum,as it is usual for lithographic printers to charge their stones, and ifthe transfer has not been quite complete, oris from old work, thisprocess should be repeated at intervals of one hour or more. When thisprocess is finished we wash all dirt and gum off with a linen rag wettedwith water, and roll over the whole plate with a soft leather rollercharged with ink, and if spots of dirt PE),- main on the plate we grindthemout with slatepencil and water. We could now (in the usualmode)printafew hundred copies from the plate; but the fine lines wouldbegin to thicken and the plate to fill up with ink, the constanttendency to do which has hitherto been a great impediment to inking andprinting by machinery. To

prevent this spreading of the ink and its adhesion to the negativelyetched or blank surface of the metalwe wash the plate over with an acidpreparation of phosphorus, which we prefer to be asolution of thesubstance called by Dulong phosphatic acid, and as termed by Davy amixture of phosphorus and phosphoric acids, mixed withgum-water. Thisacid etches in the surface partially and enables it effectually toreject the ink. By carrying this process further with strongerphosphatic acid we can obtain a palpably raised surface for printingfrom, similar to stereotype. The phosphatic acid, or combination ofphosphorus and phosphoric acids, we prepare by placing long pieces ofphosphorus upright in a glass bottle and filling it with water to withinaquarter of an inch of theirtops. Then cork the bottle, leaving anaperture of about one-sixteenth of an inch, and for admission of air welet it remain three or four days or until the wateris sufficientlyacidulated for use, which may be ascertained by placing a drop of it ona clean zinc surface, where it must produce an evident action and leavea white mark. Gum is then added to the solution and dissolved until thewhole acquires the consistence of unboiled white of egg, and the mixtureis preserved from the air in stoppered bottles.

aving now described the nature of our improvements in producing andmultiplying copies of designs and impressions of printed or writtensurfaces, we would have it understood that we do not confine ourselvesto the details shown and described, provided the peculiar character ofthearrangements or processes be retained. We would also have itunderstood that we make no claim to many of the sepa* rate parts hereindescribed; but

4,230 I t a What we claim isl. The herein-described process whereby wetransfer by means of treating the originals with acids of strengthsvarying with the induration of the ink, and so pressing out the acid asto cause an etching of the blank spaces and a reversed impression of theoriginal (where protected from the action of the acid) on metallicsurfaces.

2. The process of reviving the printing-ink on originals by first actingon them with caustic potash or its carbonate and tartaric acid, so as toform cream of tartar in the paper, which prevents the adherence of freshink in the blank spaces, while the old ink is left in a state to take upan additional quantity from a roller passed over it.

CARL FRIEDRICH BALDAMUS. [L. s] F. W. SIEMENS. [L. s} Witnesses:

THEO. S. FAY,

. See. U. S. Leg. at Berlin. JOHN ULR. WAGNER,

0f Sydney, at Berlin.

